Most of them do not rest as long as they should because they do not have a sense of time.
Note cards are better than books or calendars for looking at pictures because they are a smaller size and easier to hold. Another advantage is that they can be handed to the person, even while walking, which may help capture and sustain their attention. These pictures are a good example of a single subject foreground and a minimal background that help the person focus their attention on the information that they are able to process.
ACL 2.0 - 2.2
Avoid exhaustion while they are sitting or standing. As they get tired, their response times get slower, and their sustained attention times get shorter. If family, friends or volunteers are involved, they can be taught how to observe for signs of fatigue, and they will need instructions on who to ask to transfer the person back to bed. The complications of exhaustion are increased startle and combative reactions, more yelling and other troublesome behaviors. The consequences are apt to continue for several hours after they become exhausted.
ACL 2.4
When left to walk around all day, without a schedule or seated activities, weight loss, dehydration, exhaustion and resistance to confinement are common. Most people can recognize when they are feeling tired and need to rest. There are people who will literally walk until they drop, and when they do, they have a higher risk of falling. These people need to be identified and a schedule needs to be designed that alternates walking with seated activities. Hand-over-hand assistance will probably be needed to sustain attention while seated.